A conventional circular knitting machine mainly includes a circular cylinder to hold a plurality of vertical knitting needles and a circular sinker holder located on the circumference of the circular cylinder. The circular sinker holder holds a plurality of sinkers movable against the circular cylinder. The knitting needles and sinkers are respectively pushed by corresponding driving cams to move alternately to knit yarns.
In recent years, in order to improve quality and touch feeling of fabric, a circular knitting machine with a greater number of knitting needles has been developed. For instance, WO2012055591 discloses a knitting machine with a high gauge that includes a needle holder to hold a plurality of needles which can be driven to move alternately and axially along the needle holder, and a mechanism to guide the needles on the needle holder. Through a drawing motion of the alternate movements, the needle tip and a portion of needle stem are drawn from one end of the needle holder so that the knitted loop previously formed drops to the needle stem or one or more yarns are picked up to be fed to a yarn feeding spot or a yarn guide port. Through a retracting motion of the alternate movements, the needle together with the needle tip are retracted to the end of the needle holder to form a new knitting loop and also release the previously formed knitting loop to knitting them together. The guiding mechanism includes a channel to perform the knitting operation that is adjacent to the one end of the needle holder and a slide channel located in a zone between the needle holder and the one end of the needle holder. The channel for the knitting operation is engageable by a needle and defined with the inlet which is directed toward the outside of the needle holder the resting contact zone for knitting during the retracting motion of the needle. The number of the slide channels is less than that of the channels for performing the knitting operation.
In the conventional circular knitting machine, in order to allow the sinker to steadily move horizontally and reciprocally, aside from providing a plurality of housing slots on the circular sinker holder to hold the sinkers, the circular cylinder also has a plurality of holding slots to allow the noses of the sinkers to extend towards the knitting position above. In the aforesaid circular knitting machine with a greater number of knitting needles, when the number of the needles increases, the distance between the needles or sinkers, and the thickness of the needles and sinkers have to be shrunk. As a result, the distance between the holding slots for holding the sinkers on the circular cylinder also must be reduced. To accommodate to the technique of greater number of knitting needles, it is quite difficult to fabricate a greater number of narrow holding slots on the metallic circular cylinder, and production yield is lower as well. Moreover, as the sinkers often are in contact with the inner walls of the holding slots due to small tolerances, during knitting operation of the circular knitting machine, the thinner sinkers are easily damaged or deformed due to high temperature friction. Thus the damaged sinkers have to be replaced frequently. This is time consuming and costly.
On the other hand, during assembly and installation of the thinner sinkers, the sinkers have to be aligned precisely with the holding slots of the circular cylinder one by one. This also requires a lot of time. In the event that an error takes place in the assembly and installation, extra time and efforts are needed to do the assembly and installation anew. All this makes improving the production efficiency of the circular knitting machine with greater number of needles more difficult.